I've finally found a rich woman and don't have to work anymore.
This is a popular joke about marrying a rich woman and being set for life, basically guy's version of the classic "marrying a rich man and be set for life" fantasy.
Note the "rich woman", or literally "wealthy hag", here is referring to a specific group of women. Like the name indicates, they are usually rich in wealth and poor in beauty and youth, and most of them never married or don't have satisfactory marriages. They tend to seek comfort in places like host clubs or bars, and stories about their extreme generosity toward their favorite staff are always favored by gossip-loving tabloids and netizens.
Interestingly, the popularity of this phrase negated at least a portion of negativity of it. Although the literal meaning still applies in certain context, netizens are starting to use this to undiscriminatingly describe rich women in general.